Andrés Iniesta knows the value of the Barcelona shirt, which will soon bear the name of the Qatar Foundation. Photograph: Jasper Juinen/Getty Images

For supporters of the beautiful game off the field, as well as on it, the arrival in London of Xavi, Andrés Iniesta, Lionel Messi and their Barcelona comrades has an added poignancy. These are the final months of Barcelona's 111 years without commercial sponsorship on the club shirt, the last chance to see these artists advertising Unicef and not, bizarrely, Qatar. The right to emblazon the Gulf nation's name on the kit which has always heralded Catalonian regional pride was sold for €166m (£139m) over five years. Barcelona's member-owned, Unicef‑supporting, més que un club ("more than a club") halo has, sadly, diminished.

Cynics always said that the Unicef agreement, under which Barça pay €1.5m (£1.3m) a year to the charity, was a softening up for the idea of selling shirts bearing a commercial logo. Purists hoped it was not so. Then Qatar, a tiny state with 500,000 citizens and a gross domestic product of $126.5bn (£78.3bn), began to thrust its name on to the world stage through the use of football, that most accessible and cash-hungry medium. The project began by enticing some of Europe's great names to Qatar for pay-days at the end of their playing careers. The Barcelona manager, Pep Guardiola, played for the Qatari Al Ahli club from between 2003 and 2005, before returning to the Camp Nou.Guardiola, who said he had fallen "in love with the country", became an ambassador for Qatar's 2022 World Cup bid last year – neither the Qatari bid team nor Guardiola said whether he was paid for doing so. Qatar was announced as the 2022 host with a smile from the Fifa president, Sepp Blatter, on 2 December 2010. Only 11 days later the announcement came: Qatar's name was to appear on Barcelona's shirts. It is thought to be the first time a football club will have worn the name of a foreign country on their shirts and the deal was concluded with the largest cheque in football sponsorship history.

A statement from the Qatar Foundation, a charitable organisation run by Sheikha Mozah bint Nasser al-Missned, the wife of the ruler, Sheikh Hamad bin Khalifa al-Thani, made it clear that it was not providing the money. The finance is to be provided by Qatar Sport Investments – it will, essentially, be government money, derived from the country having the world's third-largest natural gas reserves, of 25.47 trillion cubic metres, according to the CIA's World Factbook. QSI nominated the Qatar Foundation to have its name on the Barcelona shirt.

"There are numerous benefits resulting from this deal for both countries," the statement said. These included "transfer of knowledge and expertise"; "financial support"; and "mutually shared values". But first on the list was "increased global exposure".

Barcelona, probably the greatest club name in the world, employing an iconic squad of home‑schooled virtuosos, hardly need Qatar to increase their global exposure. The club's first shirt-sponsorship deal is about less than that: it has been signed simply to boost income. Last year, Barça earned €409m (£342m) but after €335m (£280m) went on wages and other player costs (81% of turnover), they declared an €80m (£67m) loss. The club's new president, Sandro Rossell, sought a €150m (£125m) loan to bridge cashflow problems that he claimed had been left by Joan Laporta's regime. In doing so, he demonstrated the merits of mutual ownership: tired or unpopular regimes can be voted out.

Anticipating Uefa's financial fair play rules, under which clubs will have to live within their income, Barcelona have sold their shirt-sponsorship rights to make more, even though their income dwarfs that of every other La Liga club except Real Madrid. Since Rafael Benítez's 2004 title win with Valencia, no club outside the big two has won a league title that is now called "the Scottish league" by critics. The rest of the La Liga clubs have finally roused themselves to oppose individual clubs selling television rights. In 2008-09 Barcelona and Real sold theirs for €280m (£234m), the same as all other 18 clubs put together, according to Professor José María Gay of Barcelona University. The latest proposal is for rights to be sold collectively by the league, with Real and Barca keeping 17% each. Most clubs, desperate for money, have agreed. Villareal and Sevilla are maintaining their fight for more equality.

Qatar is the partner in the Barcelona deal motivated by increasing global exposure. According to Dr Christopher Davidson, reader in Middle East studies at Durham University, the country wants to go further than the nation-building of Abu Dhabi, which is being fuelled, partly, by hosting a Formula One Grand Prix and the Fifa Club World Cup and by Sheikh Mansour's acquisition of Manchester City.

"Qatar is a very small country with very much larger, potentially hostile countries, Saudi Arabia and Iran, right on its borders," Davidson says. "It makes the country and its dynastic rulers, the al-Thani family, feel more secure if it is better known in the world and sport is a very accessible way for these Arab, Gulf states to become well known and to appear open."

In his Guardian interview last week, Xavi talked about his and Barça's mantra: to look, always, for space. Qatar's al–Thanis, who have ruled their country without elections for more than 200 years, were looking for space too. They found world football's most appealing space on Barcelona's shirt. That, and all it represents, had its price.